Buggy code:
public class ModifyBlockCommand extends AbstractCommand implements Holdable , Listener { @ Override public void parseArgs ( ScriptEntry scriptEntry ) throws InvalidArgumentsException { } @ Override public void execute ( final ScriptEntry scriptEntry ) throws CommandExecutionException { final dList materials = scriptEntry . getdObject ( "materials" ) ; final List < dLocation > locations = ( ( List < dLocation > ) ( scriptEntry . getObject ( "locations" ) ) ) ; final dList location_list = scriptEntry . getdObject ( "location_list" ) ; final Element physics = scriptEntry . getElement ( "physics" ) ; final Element natural = scriptEntry . getElement ( "natural" ) ; final Element delayed = scriptEntry . getElement ( "delayed" ) ; final Element radiusElement = scriptEntry . getElement ( "radius" ) ; final Element heightElement = scriptEntry . getElement ( "height" ) ; final Element depthElement = scriptEntry . getElement ( "depth" ) ; final dScript script = scriptEntry . getdObject ( "script" ) ; final List < dMaterial > materialList = materials . filter ( dMaterial . class ) ; dB . report ( scriptEntry , getName ( ) , ( ( ( ( ( ( ( ( ( locations == null ? location_list . debug ( ) : aH . debugList ( "locations" , locations ) ) + ( materials . debug ( ) ) ) + ( physics . debug ( ) ) ) + ( radiusElement . debug ( ) ) ) + ( heightElement . debug ( ) ) ) + ( depthElement . debug ( ) ) ) + ( natural . debug ( ) ) ) + ( delayed . debug ( ) ) ) + ( script != null ? script . debug ( ) : "" ) ) ) ; final boolean doPhysics = physics . asBoolean ( ) ; final boolean isNatural = natural . asBoolean ( ) ; final int radius = radiusElement . asInt ( ) ; final int height = heightElement . asInt ( ) ; final int depth = depthElement . asInt ( ) ; if ( ( ( locations == null ) || ( ( locations . size ( ) ) == 0 ) ) && ( ( location_list == null ) || ( ( location_list . size ( ) ) == 0 ) ) ) dB . echoError ( "Must<seq2seq4repair_space>specify<seq2seq4repair_space>a<seq2seq4repair_space>valid<seq2seq4repair_space>location!" ) ; <START_BUG> if ( ( materials . size ( ) ) == 0 ) <END_BUG> dB . echoError ( "Must<seq2seq4repair_space>specify<seq2seq4repair_space>a<seq2seq4repair_space>valid<seq2seq4repair_space>material!" ) ; no_physics = ! doPhysics ; if ( delayed . asBoolean ( ) ) { new BukkitRunnable ( ) { int index = 0 ; @ Override public void run ( ) { long start = System . currentTimeMillis ( ) ; dLocation loc ; if ( locations != null ) { loc = locations . get ( 0 ) ; } else { loc = dLocation . valueOf ( location_list . get ( 0 ) ) ; } boolean was_static = preSetup ( loc ) ; while ( ( ( locations != null ) && ( ( locations . size ( ) ) > ( index ) ) ) || ( ( location_list != null ) && ( ( location_list . size ( ) ) > ( index ) ) ) ) { dLocation nLoc ; if ( locations != null ) { nLoc = locations . get ( index ) ; } else { nLoc = dLocation . valueOf ( location_list . get ( index ) ) ; } handleLocation ( nLoc , index , materialList , doPhysics , isNatural , radius , height , depth ) ; ( index ) ++ ; if ( ( ( System . currentTimeMillis ( ) ) - start ) > 50 ) { break ; } } postComplete ( loc , was_static ) ; if ( ( ( locations != null ) && ( ( locations . size ( ) ) == ( index ) ) ) || ( ( location_list != null ) && ( ( location_list . size ( ) ) == ( index ) ) ) ) { if ( script != null ) { List < ScriptEntry > entries = script . getContainer ( ) . getBaseEntries ( scriptEntry . entryData . clone ( ) ) ; ScriptQueue queue = InstantQueue . getQueue ( ScriptQueue . getNextId ( script . getContainer ( ) . getName ( ) ) ) . addEntries ( entries ) ; queue . start ( ) ; } scriptEntry . setFinished ( true ) ; cancel ( ) ; } } } . runTaskTimer ( DenizenAPI . getCurrentInstance ( ) , 1 , 1 ) ; } else { dLocation loc ; if ( locations != null ) { loc = locations . get ( 0 ) ; } else { loc = dLocation . valueOf ( location_list . get ( 0 ) ) ; } boolean was_static = preSetup ( loc ) ; int index = 0 ; if ( locations != null ) { for ( dObject obj : locations ) { handleLocation ( ( ( dLocation ) ( obj ) ) , index , materialList , doPhysics , isNatural , radius , height , depth ) ; index ++ ; } } else { for ( String str : location_list ) { handleLocation ( dLocation . valueOf ( str ) , index , materialList , doPhysics , isNatural , radius , height , depth ) ; index ++ ; } } postComplete ( loc , was_static ) ; scriptEntry . setFinished ( true ) ; } } boolean preSetup ( dLocation loc0 ) { } void postComplete ( Location loc , boolean was_static ) { } private static Field isStaticField = null ; void setWorldIsStatic ( World world , boolean isStatic ) { } void handleLocation ( dLocation location , int index , List < dMaterial > materialList , boolean doPhysics , boolean isNatural , int radius , int height , int depth ) { }

Fix:
if ( ( materialList . size ( ) ) == 0 )